They must be running some sort of macro that does a /who based on class or level, or something along those lines, and then slams tells to each. Come to think of it, I'm always anon and I never get tells.
I've always figured they had some type of automatic macro doing it cause I've gotten tells within 2 mins of logging in a few times...on one toon, then another. And I don't get them just in the common zones but its happened in far off places with only my toons in zone. And like I mentioned above, I'm usually anon ever since my best ingame friend told me its to stop people from tracking him and his 18 bots.
Quickest tell I ever got was 18 secs after I logged in (according to timestamp). So I'd be willing to guess that they are using people's names from the chat channels.
I do not join any channels and received a few. i still think high traffic zones, and you would be surprised how much traffic the tutorial gets.
OK a definitive answer here now on whether MQ2ChatFilter works on the plat spam, is it does. I added this entry in to the ini file Filter36=www.gm963.com, and then tried a tell from another of my toons with the chatfilter disabled at fiirst (plugin unloaded) then with the plugin loaded. With the plugin loaded, I did not get the tell at all from my other toon. This was with using tell windows, so in that mode it does work to filter the crap out.
Funny thing was , that with the MQ2ChatFilter plugin loaded on the toon I was sending the spam from, it would not display the line I was trying to type in, so ChatFilter works on outgoing tells also, so probably on everything you actually try to type.
I also tested it on partial matches and it does filter the entire tell on a partial string match.